Well as I am brunette and also have a medium tone of skin with a neutral undertone, I like to play with colors. Fortunately I can work with a wide variety of colors but a lot of girls have the misconception that just because a lip color is trendy they have to try it and make it work. Some people is so fair that using a tone like Poison from ABH would look weird, while on someone dark would be really flattering.
You have to know yourself and know what works with you.
Invest time researching what goes with you.. As a vampy lippie on me might be something way too dark for a very fair person, so just find a balance.. At the end makeup is to experiment, have fun and be a different person.
I did this look not so long ago and I wanted to share how it looked like.. This is more of a purple-ish tone from CyZone (Latin America Brand) and a winged eyeliner and lots of highlighter for a dewy finish. If you are medium complexion try it out and have fun!!!